Continuous film motion cinematograph projector



Jan. 16, 1934. o. c. JOHNSON CONTINUOUS FILM MOTION CINEMATOGRAPHPROJECTOR Filed Aug. 15, 1930 2 Sheets-Sheet l Jan. 16, 1934. o. c.JOHNSON CONTINUOUS FILM MOTION CINEMATOGRAPH PROJECTOR Filed Aug. 15,1930 2 Sheets-Sheet 2 UNITED STATES PATENT? OFFICE CONTINUOUS FILMMOTION CINEMATO- GRAPH PROJECTOR Oscar Charles Johnson, Woking, EnglandApplication August 15, 1930, Serial No. 475,535, and in Great BritainSeptember 2, 1929 Claims. (01. 8816.8)

The invention relates to a continuous film mowith parallel oppositelyarranged sets of teeth of tion cinematograph projector which embodiesconvenient uniform radius around the circumvery few motional parts, andin which the reference, with a circumferential channel between mainingfew stationary parts and frame are of the respective sets of teeth (Fig.3). The said 5 an extremely simple character, and cheaply mancam isfastened by a taper pin (C3) upon its drivufactured. In this apparatusthe film is com ing shaft (G1), which in turn is mounted in a tinuouslydrawn through the gate by a film bearing bush (C) fixed within theframes prosprocket, the shaft of which also carries the iecting boss(A2) and the cover bearing, Bl, reoscillating mirror or prism operatingcam, in adspectively.

l0 dition to the shutter driving wheel or gear fas- The cam spindle, 01,carries near one end a tened thereto. The mirror or prism shaft rockerfilm sprocket, C2, while the shafts opposite end is operated directlyoff the said cam, and during is furnished with a fly-wheel pulley, H,incorall operating periods is locked relatively to the porating afriction clutch, and consists of a chain cams contour, whereby obviatingany local oscilwheel sprocket, H1, mounted upon the pulleys 15 lation,in addition eliminating gear wheel train boss, H2, formed with a collar,H3; the inner side 7 or other complicated transmission systems beof thesaid chain wheel, H1, is pressed against the tween the continuouslyrevolving film sprocket collar, H3, by similar collar plate, H4, loadedand the oscillating mirror or prism, thus elimipreferably by two helicalsprings, S and S1, held nating gear wheel back-lash, wear, bearing-playin position by screws K and K1. Against the 20 and constructional errorsembodied more or less contour of cam G bear the ends of a rocker or invarious transmission systems. The result is lever, L, each end of thelatter being engaged that a perfectly steady picture is projected, evenwith its own operating sets of teeth (Figs. 1 and after continuous use.The said cam shutter wheel 3) the rocker or lever, L, is preferablycentrally and prism or mirror-rockers are enclosed in an secured at oneend of a shaft, W, preferably by 0il-bath formed by a projecting part ofthe frame, a friction grip functioned by screw L1. The 39 and having acover-plate. They are so arranged rockers shaft, W, is mounted in anadjustable that after removing the driving fly-wheel pulley body, E,which functions the part of a bearing clutch (hereinafter described)which is secured and is formed with a flange, El, for fastening to themain shaft, the cover-plate may be reby screws, E4 and E5, to the bossA3 of frame A;

so moved for inspection of the few motional parts the adjusting screwsE2 and E3 of flange El fur 5 when they are either stationary or inmotion. nish means whereby the body E and consequently The film-gate isreadily adjustable in its distance its supported shaft, W, together withrocker, L, from the mirror, thereby correcting the angular may beadvanced or retracted and so alter the motion of the prism or mirror tocompensate for bearing pressure between the rockers extremities 35varying widths of film, and for wear of cam, if and the cams contourrespectively. The other any. end of the rocker-operating shaft, W, isformed The apparatus preferably employs a known preferably with aslotted cylindrical head, F2,

optical system, which consists of a pair of lenses into which is secureda reflecting glass prism, F4, arranged in tandem, with a fixed maskplate inby a friction grip effected by drawing the upper terposed, itsaction relatively to the projector and lower parts of the slotted headupon the mechanism being hereinafter described. The prism by screw F3.If a reflecting mirror be emprojector could be easily adapted tosound-synployed in preference to a prism, shaft W is chronized systems,thus simplifying the latter formed with a ring into which is fitted thesaid apparatus. The accompanying drawings, by way mirror. The prism ormirror is amply protected 45 of example, illustrate an apparatus adaptedfor by a strong metallic cover, F, fitting over the carrying myinvention into effect. Figure 1 enlarged end, E6, of body E. The twoapertures shows a part-sectional plan; Figure 2 a side-ele- F1 and F5permit the light-beam to enter and vation thereof; Figure 3 the sideelevation of the emerge via the prism or mirror. The preferablyoperating cam, and Figure 4 a plan of the filmtwo-bladed, extremelynarrow shutter, D3, is

50 gate. fastened by a collar, D2, to a shaft, D, mounted The projectorframe or body A (Fig. 1) is in a bearing bush, D1, secured in the framesformed with an oil chamber, A1, closed by means lateral boss, A4, by aset screw, D4. The inner end of a cover, B, secured thereto by screws,B2, and of shaft D is furnished with a bevel wheel, D5, incorporates abearing, B1. In this closed chamdriven by a further bevel wheel, D6,fastened to 55 her, A1, is mounted the operating cam, G, formed theoperating cam, G, by screws G1 and G2.

A sprocket film roller, X, pivoted to a springloaded arm, X1, holds thefilm upon the sprocket, C2. The said arm, being pivoted to frame A in asuitable position, is furnished with a film guide roller, X2.

The film gate consists of a body, N (Figs. 2 and 4) fastened preferablyat the top of the frame, A, at a convenient angle by screws, Ni and N2,and incorporates a pair of gate rum which form part of a plate, M,fastened by the screws M1 and M2 to the top side of body N. This saidplate is provided with an aperture, J, equal in length to two filmpictures. A back-plate formed with similar aperture J and a pair of gaterunners, is pivoted by its two projecting arms, J2 and J3, to the body,N, by a spindle, J4, and, loaded with springs, O, completes the filmtrap. The cut-away portion, P, permits the light beam to pass throughthe said a erture. The lever, V, pivoted at V1 to the gate body, N, inconjunction with the film roller, V 2, permits the film to be centredduring the projection period. The screws N3 and N4 of body N (Figs. 2and 4) are for adjusting, within limits, the distance between the filmtrap and prism F4, or mirror, to compensate for wear in the operatingmechanism.

A bracket, R, is preferably fastened at the front end of frame A,vertically, by screws R1 and and incorporates an aperture, R4, overwhich is tted a mask plate, R3, provided with a picture mask, R5. Thebracket, 3, is furnished with two parallel horizontal rods, R6 R7, uponwhich are mounted two lens jackets, Z and Z1, jacket Z being situated infront of the prism or mirror, and furnished with a large aperture lens,Z2, of predetermined focal length, preferably standard type ofprojection lens, capable of longitudinal motion. This motion is effectedby the operating lever T, pivoted at one end to the bracket R andconnected to the lens jacket Z by a connecting link, T1.

The other lens jacket, Z1, is situated in front of the picture maskplate R3 and R5, and is furnished with a large aperture, preferablystandard type of projection lens, Z3, of any convenient focal length.Focussing is effected by a disc, Z4, which imparts a rotary motion topinion Z5, the latter engaging with a rack, Z6, or rod R6, the pinion Z5being held in contact with rack, Z6, and position by a bearing plate,Z7.

Spool arms of suitable design are fastened to the frame A in aconvenient position and furnished with spool-boxes of an approvedpattern, the take-up spool being driven by a chain of standard designfrom the chain-sprocket wheel. H1.

The action of my invention is as follows:Assume that the projector isthreaded with a film so that two full pictures will occupy the gateaperture, and are numbered 1, 2; and the following hidden picture isnumbered 3 for explanatory purposes. Also assume that the gate aperture,J, is flooded with a light-beam from a light source within thelamp-house. A real, sharp image is now cast via the reflecting prism F4,or mirror, upon the mask-plate, R3, by the predetermined focus lens, Z2,of the two said pictures. Upon turning the projector by hand or motorpower, the film sprocket C2 gradually draws the film through the gate,whereby No. 2 picture gradually replaces the original position of No. 1picture, the corresponding film-change being counterbalanced by theprism F4 or mirror receiving a very small predetermined angular motionin the same direction as the moving film.

The angular motion of the prism F4, or mirror, is effected by the camsrotary motion, imparted by the sprocket spindle, Cl, whereby one of theteeth G3 (Fig. 3) of cam G elevates one end of prism shaft rocker L,while the oppositely arranged parallel tooth, G4, of the cam permits theother end of rocker L to be lowered simultaneously. The combined effectof the moving film and the angular moving prism F4 or mirror is that themoving images are rendered stationary upon the mask-plate, R3, while thelight-beam and perimeter image of the gate apertiu'e J move accordingly.Upon No. 2 picture fully replacing the original position of N0. 1picture, and consequently, No. 3 replacing No. 2, the extremities of therespective two oppositely arranged teeth, G3 and G4 are reached.Whereupon the following pair of teeth returns the rocker L and itscomponent parts to their original position at an extremely rapid rate,the shutter, D3, simultaneous- 1y covers the picture mask R5, and theabove cycle of operations is repeated during the projection period. Thepicture mask, R5, permits only one of the two images to be projected bythe projection lens, Z3, upon a screen suitably placed.

It will be readily observed that the respective distance between thegate and reflecting prism F4 or mirror is of ample dimensions, therebypermitting an exceedingly small angular motion of prism F4 or mirror andits component parts. These, in turn, may be made very small andconsequently very light, thus reducing the inertia to a negligibleamount, and so permitting almost any rate of change without impairingthe endurance or reliability of action.

Having now particularly described and ascertained the nature of my saidinvention, and in what manner the same is to be performed, I declarethat what I claim is:

1. A continuous film-motion cinematograph comprising a frame formed witha. main bearing co-axial with a formed, projecting oil-chamber whichincorporates a lateral bearing-boss and is provided with a cover-plate;the frame having also secured to it a flange forming part of anadjustable bearing parallel with the main bearing; the main bearingcarries a shaft on which is fixed, outside the oil-chamber, afilm-operating sprocket in close proximity to the film gate, which issecured by screws at a convenient angle on the top of the frame, and inaddition to carrying the film sprocket, the main shaft carries anoperating cam situated within the oil-chamber and formed with parallel,oppositely arranged pairs of teeth which actuate the extremities of arocker centrally secured to a, shaft mounted in the adjustable bearingand carrying at the opposite extremity an oscillating reflector in linewith the gate-aperture; the cam has fastened to it a gear wheel directlyengaged with another wheel secured to a shaft mounted in the lateralbearing-boss and carrying the light-shutter; these parts being sosynchronized in movement that a point of the moving film is renderedstationar after reflection, by the oscillating reflector between theshutter occultations.

2. In projection mechanism as defined in claim 1, the adjustable bearingcarries the reflector shaft with reflector and its actuating rocker,thus forming a complete unit which may be advanced, retracted or fixedin order to provide relative adjustment between the rocker extremitiesand the pair of oppositely-arranged, parallel teeth engaged at thatmoment; the adjustment being iio effected by means of screws in a flangewhich forms part of the bearing body.

3. In mechanism as defined in claim 1 the cams parallel,oppositely-arranged pairs of teeth are so related to the reflectoroperating shaft rocker extremities that one tooth of a pair elevates oneend of the rocker, while the other tooth permits the other end of therocker to be lowered simultaneously, thus locking the said rockerextremities to the face of the cam during both the normal and thequick-return operating periods.

4. In projector mechanism as defined in claim 1, the oscillatingreflector is protected from damage by a removable, fixed, cylindricalcover OSCAR CHARLES JOHNSON.

